C# Problem with Oauth

I am trying to create oauth signature. But I dont know what I am doing wrong because the site giving unauthorize error. I am using oauth version 1.0. Method is HMAC-SHA1 and it is google based oauth. My base string is correct because it checked it with sample output. My code :

string oauthSig = "";
        string baseString = HttpUtility.UrlEncode(httpMethod.ToUpper()) + "&" +开发者_如何学C
                            HttpUtility.UrlEncode(url) + "&" +
                            HttpUtility.UrlEncode("oauth_callback="+callback+"&"+
                                                  "oauth_consumer_key="+consumerKey+"&"+
                                                  "oauth_nonce="+nounce+"&"+
                                                  "oauth_signature_method="+sigMethod+"&"+
                                                  "oauth_timestamp=" + timestamp + "&" +
                                                  "oauth_version=" + version
                                                  );
        HMACSHA1 myhmacsha1 = new HMACSHA1(Encoding.UTF8.GetBytes(HttpUtility.UrlEncode(consumeSecret)),true);
        byte[] hashValue = myhmacsha1.ComputeHash(Encoding.UTF8.GetBytes(baseString));
        oauthSig = Convert.ToBase64String(hashValue);

Please tell me if I am doing anything wrong.

Thanks

The key to the signature should be:

CONSUMER_SECRET + '&' + TOKEN_SECRET

And since you do not have a token secret yet, you should use CONSUMER_SECRET and an ampersand (&) as the key to the signature.

Edit, further clarification:

HMACSHA1 hmacsha1 = new HMACSHA1();
hmacsha1.Key = Encoding.ASCII.GetBytes(string.Format("{0}&{1}", UrlEncode(consumerSecret), string.IsNullOrEmpty(tokenSecret) ? "" : UrlEncode(tokenSecret)));

byte[] dataBuffer = System.Text.Encoding.ASCII.GetBytes(data);
byte[] hashBytes  = hmacsha1.ComputeHash(dataBuffer);

return Convert.ToBase64String(hashBytes);

I've not tested the code but i've taken it from from oauth.googlecode.com - OAuthBase.cs. I highly recommend checking it out, it should do everything you want.